Locking security knobs are generally well-known.
One well-known locking-type security knob is the DuraSafe locking knob available from DuraSafe Inc., New Berlin, Wis., United States of America. Such locking-type security knobs are large, cumbersome, expensive to manufacture and are expensive to the purchaser because of an integral lock mechanism at the core.
However, locking-type security knobs are inherently restricted from providing efficient and reliable security without an actual lock mechanism.